thumbs-up.png
https://www.iconfinder.com/icons/83403/thumbs_up_icon#size=32
Creative Commons (Attribution-Share Alike 3.0 Unported)

thumbs-down.png
https://www.iconfinder.com/icons/83402/down_thumbs_icon#size=32
Creative Commons (Attribution-Share Alike 3.0 Unported)